The pretectum as a site for relaying dorsal column input to thalamic VL neurons.

Intracellular recording techniques were used to study dorsal column input to 122 feline ventral thalamus (VL) relay neurons, before (61 cells) and after (61 cells) lesioning the pretectum. Prior to the lesions, 75% (46/61) of the neurons responded with short and longer latency postsynaptic potentials to dorsal column stimulation. Latencies of the postsynaptic potentials ranged from 4 (short) to 20 ms (long). After the lesions, only long latency responses were encountered, and those responses were seen in only 16% (10/61) of the cells. These data indicate that the pretectum may play an important role in mediating dorsal column information to VL, ultimately influencing cerebellar commands to the motor cortex.